Technical Field
Example embodiments generally relate to a regulator and a method for operating same and particularly, but not exclusively to a dual mode regulator for an amplifier.
Description of the Related Art
Amplifiers that are part of equipment used at base stations to amplify signals received by and/or transmitted to power equipment to remotely control the orientation of one or more antennas positioned at a tower of a base station. Many of these amplifiers are mounted at the top of a tower of a base station and are thus referred to as Tower Mounted Amplifiers (TMA). TMAs operate in accordance with a certain standard called the Current Window Alarm (CWA) mode. The CWA mode of operation, which is a legacy mode of operation, is still used in many base station towers. In the CWA mode, the regulators for the amplifiers used at the base station are required to operate for a range of input voltages provided by the base station equipment while providing a constant DC current (having a defined amplitude) to the amplifiers. Further, the regulators are to monitor the current used by the amplifiers and enter an alarm mode if such current becomes appreciably greater than the defined constant amplitude level. Moreover, while in the alarm mode, the regulators are required to sink an alarm current by changing the duty cycle of the PWM pulses applied to a current load to achieve a desired DC current amplitude. That is, the regulators are able to intentionally sink large currents being provided by the base station to generate this alarm signal. Linear regulators are used in these CWA systems because linear regulators are able to provide a constant current for a range of input voltages. However, these linear regulators achieve this feature by simply dissipating the additional current they need to meet the constant current requirement or the large current they need to generate the alarm signal through resistive loads. As such these CWA legacy systems are very inefficient as they waste relatively large amounts of energy to meet their operational requirements.
The switching regulator is widely used for its high energy efficient operation. These regulators operate in accordance with the Antenna Interface Standards Group (AISG), which allows exchange of messages (formatted as per a certain recognized protocol) between the base station equipment and the TMAs that remotely control the electrical tilt of antennas mounted at the top of base station towers. AISG messages are exchanged in a virtually continuous fashion between tower mounted equipment and other base station equipment. In addition to the switching regulators being energy efficient (relative to the linear regulators), there is no requirement for generating an energy wasting alarm signal such as the alarm signal required by base stations still operating in accordance with the CWA mode. In the AISG base stations, a message informing of an alarm condition is simply used to inform the base station of the occurrence of an alarm.
Unfortunately, many communication systems still use antenna systems that still adhere to the CWA approach. However the need and desire for AISG type approach is clear.